Chapter 17 02/10/2014
Three new disciplines promotes a growing a growing awareness of change.
Vestigial structures the useless body parts we observe today, must have functioned in ancestral
Catastrophism reasoning that each layer of fossils represented the remains of organism that died in a local
catastrophe such as a flood.
Principle of use and disuse body parts grow in a proportion to how much they are used, any anyone who
pumps iron well knows.
Inheritance of acquired characteristics changes that an animal acquires during its lifetime are inherited by
Lamarck made four important contributions to the development of an evolutionary worldwide:
He proposed that all species change through time.
He recognized that changes are passed from one generation to the next.
He suggested that organisms change in response to their environments.
He hypothesized the existence of specific mechanisms that caused evolutionary change.
Plate tectonics be responsible for phenomena such as continental drift and have strong influence on the
distribution and evolution of organisms.
Changes in Earth’s crust can also cause calamitous events such as earthquakes, which also have
implications for living organisms.
Four Characteristics distinguish Darwin’s theory from earlier explanations of biological diversity and
Darwin provided purely physical rather than spiritual explanations about the origins of biological diversity.
Darwin recognized that evolutionary change occurs in groups of organisms rather than an individuals.
Some members of a group survive and reproduce more successfully than others do.
Darwin described evolution as a multistage process. Variations arise within groups, natural selection
eliminates unsuccessful variations, and the next generation inherits successful variations.
Like Lamarck, Darwin understood that evolution occurs because some organisms function better than
others in a particular environment. 17.3f
Darwin argued that all organism that ever lived arose through descent with modification, the evolutionary
alteration and diversification of ancestral species.
Darwin proposed natural selection as the mechanism that drives evolutionary change.
Scientists can assign relative and absolute ages to geologic strata and the fossils they contain.
The geologic time scale provides a relative dating system for sedimentary strata rather than actual ages of
rocks and fossils.
Radiometric dating involves the use of isotopes and sometimes allows actual ages to be associated with
different rock strata.
Scientists use the ratio of 14C to 12C present in a fossil to determine its age.
Continuous and Disjunct Distributions
Many species have a continuous distribution, living in suitable habitats throughout large areas.
Disjunct Distributions species live in a widely separated locations.
Dispersal is the movement of organisms away from their place of origin; it can produce a disjunct
distribution if a new population becomes established on the far side of a geographic barrier.
Vicariance is the fragmentation of a continuous geographic distribution by external factors.